An heir presumptive or heiress presumptive is the person entitled to inherit a throne, peerage, or other hereditary honour, but whose position can be displaced by the birth of an heir apparent, male or female, or of a new heir presumptive with a better claim to the position in question.[1][2] The position is however subject to law and/or conventions that may alter who is entitled to be heir presumptive.

Depending on the rules of the monarchy the heir presumptive might be the daughter of a monarch (if males take priority over females and the monarch has no sons), or the senior member of a collateral line (if the monarch is childless); the birth of a legitimate child to the monarch will displace the former heir presumptive by a new heir apparent or heir presumptive. It is not assumed that the monarch and his or her consort are incapable of having further children; the day before Queen Elizabeth II ascended the throne her father was gravely ill and her mother was in her early 50s, but Elizabeth was still considered the heir presumptive rather than the heir apparent.

Heir presumptive, like heir apparent, is not a title or position per se. Rather, it is a general term for a person who holds a certain place in the order of succession. In some monarchies, the heir apparent bears, ipso facto, a specific title and rank (e.g., Denmark, Netherlands, United Kingdom), this also sometimes being the case for noble titleholders (e.g., Spain, United Kingdom), but the heir presumptive does not bear that title. In other monarchies (e.g., Monaco, Spain) the heir to the throne bears a specific title (i.e., "Hereditary Prince/Princess of Monaco", "Prince/Princess of Asturias") by right, regardless of whether she or he is heir apparent or heir presumptive.

An heir can fail to inherit for other reasons than displacement, for example by death or incapacity of the heir, abolition of the title, or changes to the rules of inheritance.

In the English common law of inheritance, there is no seniority between sisters; where there is no son to inherit, any number of daughters share equally. Therefore, certain hereditary titles can have multiple simultaneous heirs presumptive. Since the title cannot be held by two people simultaneously, two daughters (without a brother) who inherit in this way would do so as co-parceners and before they inherit, both would be heirs presumptive. In these circumstances, the title would in fact be held in abeyance until one person represents the claim of both, or the claim is renounced by one or the other for herself and her heirs, or the abeyance is ended by the Crown. There are special procedures for handling doubtful or disputed cases.

In the Disney animated film The Lion King, Scar is the heir presumptive of the Pride Lands, his inheritance being displaced by the birth of Simba, the heir apparent, thus sparking the entire plot of the film.

In the first three series of the television series Downton Abbey, much of the drama centred on Matthew Crawley, the heir presumptive to the current Earl of Grantham, Robert Crawley, following the death of two closer cousins. For several months Matthew was at risk of being displaced, as Robert's wife Cora experienced a late-life pregnancy. The Countess eventually lost the baby; a boy. Upon Matthew's death at the end of series 3, his son took his place as heir presumptive.

In Pair of Kings, the Kings' cousin Lanny is the next in line to become King of Kinkow after his cousins (who reign together) die but his place depends on all his cousins remaining childless.

In Frozen, Princess Anna, as Queen Elsa's younger sister, is the next in line.

In the 2011 reboot of ThunderCats, Tygra, as the adopted son of King Claudus, was heir presumptive to the throne of Thundera before being displaced by the birth of Lion-O.

In Game of Thrones, Ramsay Bolton kills his father and his newborn half-brother as he was the heir presumptive while his new brother was heir apparent.